Two piece rail system for firearm

ABSTRACT

A firearm handguard having two identical halves, or half guards, can engage the barrel nut of certain firearms to thereby provide a mounting rail system. The barrel nut attaches the barrel to the receiver. The half guards can be separately positioned in engagement with the barrel nut before fastening them together. The fastening operation can cause the half guards to clamp onto the barrel nut. Alternatively, the front handguard cup of some firearms can prevent the handguard from slipping forward while the rear barrel nut engagement prevents handguard rotation. Free floating variants, however, must clamp onto the barrel nut.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the priority and benefit of U.S. Provisional Patent Application No. 61/143,795 filed on Jan. 11, 2009 entitled “Firearm Vertical Fore Grip and Rail System” and which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments relate to the fields of small arms, rifle handguards, carbine handguards, and mounting rails.

BACKGROUND

Current small arms use mounting rail systems for attaching accessories to the small arm. For example, M4 and M16 carbines are often fitted with a single piece handguard that incorporates up to four Picatinny rails. Picatinny rails are well known mounting rails that meet the specifications contained in MIL-STD-1913 and MIL-STD-1913 Notice 1. Another mounting rail called the Weaver rail is a notoriously well known variation of the Picatinny rail. Battaglia discloses a mounting rail system in U.S. Pat. No. 6,792,711 while Olson discloses another in U.S. Pat. No. 5,826,363.

FIG. 1, labeled as “Prior Art”, illustrates a handguard 101 with four mounting rails 102 of which three are visible. A number of accessories have been developed to attach to small arms by way of mounting rails 102. The mounting rails have recoil grooves 103 that help lock accessories in place and help users attach accessories in repeatable positions.

FIG. 2, labeled as “Prior Art”, illustrates an M16 type firearm 201 with mounting rails 102. The specific rifle is a flat top model having a mounting rail 102 on the upper receiver 202 as well as the four on the handguard 101. The handguard 101 is attached to the firearm by being pushed into a front handguard cup 204 by a delta ring 203.

FIG. 3, labeled as “Prior Art”, illustrates a barrel nut 301 having a barrel nut sprocket 302. The barrel nut sprocket 302 has numerous teeth 303 that can provide a gripping surface for turning the barrel nut 301.

FIG. 4, labeled as “Prior Art”, illustrates a barrel nut 301 attaching a barrel 401 to a firearm receiver 202. The barrel nut 301 is tightened onto the receiver 202 by gripping the barrel nut sprocket 302 and twisting. A special tool is often used to tighten the barrel nut 301 until the barrel nut 301 and the barrel 401 are firmly attached to the receiver 202.

Typically, the handguard is a “clamshell” arrangement made of two pieces, an upper piece and a lower piece, that fit between the delta ring 203 and front handguard cup. As such, the handguard is not as rigidly attached as is often desired. Systems and methods for rigidly attaching a handguard with integral mounting rails are needed.

BRIEF SUMMARY

The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

Systems and methods are needed for rigidly attaching a handguard with integral mounting rails to a firearm that uses a barrel nut to attach a barrel to the receiver. The barrel nut has a toothed barrel nut sprocket for gripping and turning the barrel nut.

The handguard includes two identical half guards fastened together. Each half guard has a mounting rail, an inner engagement, an outer engagement, and a portion that engages the barrel nut, typically at the barrel nut sprocket. The half guards are semi-cylindrical such that an assembled handguard is cylindrical. Fasteners passing through open holes in the outer engagements are threaded into threaded holes in the inner engagements. A complete, rigid, and cylindrical handguard is produced when the fasteners are tightened.

Tightening the fasteners can cause the handguard to clamp onto the barrel nut or barrel nut sprocket. Optionally, the half guards can include clamping mechanisms such that an assembled handguard can be slipped onto a barrel nut and clamped directly onto it. In some embodiments, the half guards include sprocket slots such that the sprocket slot of each half guard is slipped onto the barrel nut socket before the half guards are fastened together.

The half guards can incorporate elements to prevent the assembled handguard from rotating around the barrel nut. In some embodiments, the half guards themselves are machined, molded, or cast to include indentations that match the teeth of the barrel nut sprocket. Other embodiments can have slots into which pins fit and engage the teeth to prevent rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer to identical or functionally similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the background of the invention, brief summary of the invention, and detailed description of the invention, serve to explain the principles of the present invention.

FIG. 1, labeled as “Prior Art”, illustrates a handguard with four mounting rails of which three are visible;

FIG. 2, labeled as “Prior Art”, illustrates an M16 type firearm with mounting rail;

FIG. 3, labeled as “Prior Art”, illustrates a barrel nut having a barrel nut sprocket;

FIG. 4, labeled as “Prior Art”, illustrates a barrel nut attaching a barrel to a firearm receiver;

FIG. 5 illustrates a quarter front view of a half guard in accordance with aspects of some embodiments;

FIG. 6 illustrates a quarter back view of a half guard in accordance with aspects of some embodiments;

FIG. 7 illustrates a rear view of a first half guard in accordance with aspects of some embodiments;

FIG. 8 illustrates a rear view of a second half guard in accordance with aspects of some embodiments;

FIG. 9 illustrates a rear view of a first half guard and a second half guard positioned together in a radially opposed arrangement in accordance with aspects of some embodiments;

FIG. 10 illustrates a quarter back view of a half guard in accordance with aspects of some embodiments;

FIG. 11 illustrates a quarter back view of a half guard with a clamping fastener and pin in accordance with aspects of some embodiments;

FIG. 12 illustrates a quarter back view of a free floating type handguard in accordance with aspects of some embodiments;

FIG. 13 illustrates a tapered head fastener and oversize countersunk open hole for clamping two half guards together in accordance with aspects of some embodiments; and

FIG. 14 illustrates a fastener clamping two half guards together in accordance with aspects of some embodiments.

DETAILED DESCRIPTION

The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof. In general, the figures are not to scale.

A firearm handguard having two identical halves, or half guards, can engage the barrel nut of certain firearms to thereby provide a mounting rail system. The barrel nut attaches the barrel to the receiver. The half guards can be separately positioned in engagement with the barrel nut before fastening them together. The fastening operation can cause the half guards to clamp onto the barrel nut. Alternatively, the front handguard cup of some firearms can prevent the handguard from slipping forward while the rear barrel nut engagement prevents handguard rotation. Free floating variants, however, must clamp onto the barrel nut.

FIG. 5 illustrates a quarter front view of a half guard 501 in accordance with aspects of some embodiments. The front half guard has mounting rails 102, open holes 504, threaded holes 502, and a cup engagement 503. The open holes 504 can be countersunk so that the heads of fasteners do not stick out. The cup engagement 503 is designed to fit into a firearm's front handguard cup.

FIG. 6 illustrates a quarter back view of a half guard 501 in accordance with aspects of some embodiments. The back view shows indentations 601 that can engage the teeth 303 of the barrel nut sprocket 302 to keep the half guard 501, or fully assembled handguard, from rotating around the barrel nut 301. The inner engagement 602 and outer engagement 603 are more easily visible than in the previous figure.

FIG. 7 illustrates a rear view of a first half guard in accordance with aspects of some embodiments. The indentations 601 are clearly visible as is the radially opposed arrangement of the inner and outer engagements.

FIG. 8 illustrates a rear view of a second half guard in accordance with aspects of some embodiments. The second half guard 501 is identical to the first half guard 501 but rotated 180 degrees.

FIG. 9 illustrates a rear view of a first half guard 501 and a second half guard 501 positioned together in a radially opposed arrangement in accordance with aspects of some embodiments. When fastened together, the two half guards 501 form a handguard 901. Note that the inner engagements and the outer engagements are aligned so that a fastener passing through an open hole immediately encounters a threaded hole such that the two half guards can be fastened together. The fasteners should not intrude into the handguard interior where they might interfere with the firearm barrel, gas tube, or other element.

FIG. 10 illustrates a quarter back view of a half guard 1001 in accordance with aspects of some embodiments. This half guard 1001 lacks a cup engagement because it is intended for a free floating handguard. A free floating handguard is a handguard that, ideally, does not touch the barrel at all although some arrangements do contact the barrel where it meets the receiver. The half guard 1001 has a pin slot 1003 and a sprocket slot 1002. The barrel nut sprocket fits into the sprocket slot 1002 such that the half guard 1001 can not slip forward along the barrel when properly positioned on a firearm.

The half guard of FIG. 10 also has a clamping mechanism. A clamping fastener can pass through open clamp hole 1004 and be threaded into threaded clamp hole 1005. When tightened, the clamping fastener can cause clamping surface 1006 to bear down and press against the barrel nut and thereby clamp an assembled handguard to the barrel nut.

FIG. 11 illustrates a quarter back view of a half guard 1001 with clamping fasteners 1102 and a pin 1101 in accordance with aspects of some embodiments. The pin 1101 is positioned in pin slot 1003 such that it can engage the barrel nut sprocket teeth to prevent the handguard from rotating around the barrel nut. The clamping fasteners 1102 are properly inserted into the half guard. Notice that two clamping fasteners 1102 are illustrated whereas, in practice, one or more can be used.

FIG. 12 illustrates a quarter back view of a free floating type handguard 1201 in accordance with aspects of some embodiments. Two half guards 1001 are properly positioned in radial opposition to one another. The fasteners for attaching the two halves 1001 together are not shown.

FIG. 13 illustrates a tapered head fastener 1301 and oversize countersunk open hole 1302 for clamping to two half guards together in accordance with aspects of some embodiments. The oversize countersunk open hole 1302 is in the outer engagement 603 and a threaded hole 502 is in the inner engagement 602. Tightening the fastener 1301 causes the tapered head to press down into the countersunk hole 1302 and pull two half guards together. The result can be that the half guards, when pulled together, clamp onto the barrel nut, perhaps at the barrel nut sprocket portion of the barrel nut.

FIG. 14 illustrates a fastener 1401 clamping to two half guards together in accordance with aspects of some embodiments. Tightening the fastener 1401 pulls the two parts together such that a clamping action is achieved.

It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. 

1. A handguard for a firearm, the firearm comprising a receiver and a barrel nut threaded onto the receiver, wherein the barrel nut comprises a barrel nut sprocket, and wherein the handguard comprises: a first half guard comprising a mounting rail, inner engagement, outer engagement, and a means for engaging the barrel nut sprocket wherein the first half guard is semi-cylindrical with the inner engagement and the outer engagement radially opposed to one another, wherein the outer engagement comprises at least one open hole, and wherein the inner engagement comprises at least one threaded hole; a second half guard identical to the first half guard; and a plurality of threaded fasteners that pass through the open holes and thread into the threaded holes to thereby attach the first half guard and the second half guard together in a radially opposed arrangement and wherein the threaded fasteners are tightened to thereby clamp the means for engaging the barrel nut sprocket onto the barrel nut sprocket.
 2. The handguard of claim 1 wherein the barrel nut sprocket comprises a plurality of teeth, wherein the means for engaging the barrel nut sprocket comprises a plurality of indentations that engage the sprocket teeth and prevent the handguard from rotating around the barrel nut.
 3. The handguard of claim 2 wherein the fasteners are loosened but not removed to release the handguard from the barrel nut sprocket and to thereby render the handguard removable from the firearm.
 4. The handguard of claim 1 wherein the fasteners are loosened but not removed to release the handguard from the barrel nut sprocket and to thereby render the handguard removable from the firearm.
 5. The handguard of claim 1 wherein the barrel nut sprocket comprises a plurality of teeth, wherein the means for engaging the barrel nut sprocket comprises a plurality of indentations that engage the sprocket teeth to prevent the handguard from rotating around the barrel nut.
 6. The handguard of claim 1 wherein the firearm further comprises a front handguard cup and wherein the first half guard further comprises a cup engagement that fits into the front handguard cup to thereby retain the first half guard between the receiver and the front handguard cup.
 7. A handguard for a firearm, the firearm comprising a receiver and a barrel nut threaded onto the receiver, wherein the barrel nut comprises a barrel nut sprocket, and wherein the handguard comprises: a first half guard comprising a mounting rail, inner engagement, outer engagement, and a means for engaging the barrel nut sprocket wherein the first half guard is semi-cylindrical with the inner engagement and the outer engagement radially opposed to one another, wherein the outer engagement comprises at least one open hole, and wherein the inner engagement comprises at least one threaded hole; a second half guard identical to the first half guard; a plurality of threaded fasteners that pass through the open holes and thread into the threaded holes to thereby attach the first half guard and the second half guard together in a radially opposed arrangement; and at least one clamping fastener passing through the means for engaging the barrel nut sprocket wherein the means for engaging the barrel nut sprocket clamp onto the barrel nut sprocket when the clamping fastener is tightened and to thereby attach the handguard to the receiver as a free floating handguard.
 8. The handguard of claim 7 wherein the means for engaging the barrel nut sprocket comprises a sprocket slot that slips over the sprocket to thereby attach the handguard to the barrel nut.
 9. The handguard of claim 8 further comprising a pin, wherein the first half guard further comprises a pin slot, wherein the barrel nut sprocket comprises a plurality of teeth, wherein the pin fits into the pin slot to thereby engage the teeth and prevent the handguard from rotating on the barrel nut.
 10. The handguard of claim 7 further comprising a pin, wherein the first half guard further comprises a pin slot, wherein the barrel nut sprocket comprises a plurality of teeth, wherein the pin fits into the pin slot to thereby engage the teeth and prevent the handguard from rotating on the barrel nut.
 11. A handguard for a firearm, the firearm comprising a receiver and a barrel nut threaded onto the receiver, wherein the barrel nut comprises a barrel nut sprocket, and wherein the handguard comprises: a first half guard comprising a mounting rail, inner engagement, outer engagement, and a means for engaging the barrel nut sprocket wherein the first half guard is semi-cylindrical with the inner engagement and the outer engagement radially opposed to one another, wherein the outer engagement comprises at least one open hole, and wherein the inner engagement comprises at least one threaded hole; a second half guard identical to the first half guard; and a plurality of threaded fasteners that pass through the open holes and thread into the threaded holes to thereby attach the first half guard and the second half guard together in a radially opposed arrangement.
 12. The handguard of claim 11 wherein the barrel nut sprocket comprises a plurality of teeth, wherein the means for engaging the barrel nut sprocket comprises a plurality of indentations that engage the sprocket teeth and prevent the handguard from rotating around the barrel nut.
 13. The handguard of claim 12 wherein the fasteners are tapered fasteners and wherein the open holes are oversize and countersunk such that the first half guard and the second half guard pull towards each other as the fasteners are tightened to thereby clamp the handguard onto the barrel nut.
 14. The handguard of claim 13 wherein the firearm further comprises a front handguard cup and wherein the first half guard further comprises a cup engagement that fits into the front handguard cup to thereby retain the first half guard between the receiver and the front handguard cup.
 15. The handguard of claim 11 further comprising a pin, wherein the first half guard further comprises a pin slot, wherein the barrel nut sprocket comprises a plurality of teeth, wherein the pin fits into the pin slot to thereby engage the teeth and prevent the handguard from rotating on the barrel nut.
 16. The handguard of claim 15 wherein the fasteners are tapered fasteners and wherein the open holes are oversize and countersunk such that the first half guard and the second half guard pull towards each other as the fasteners are tightened to thereby clamp the handguard onto the barrel nut.
 17. The handguard of claim 16 wherein the means for engaging the barrel nut sprocket comprises a sprocket slot that slips over the sprocket to thereby attach the handguard to the barrel nut.
 18. The handguard of claim 11 wherein the firearm further comprises a front handguard cup and wherein the first half guard further comprises a cup engagement that fits into the front handguard cup to thereby retain the first half guard between the receiver and the front handguard cup.
 19. The handguard of claim 11 wherein the fasteners are tapered fasteners and wherein the open holes are oversize and countersunk such that the first half guard and the second half guard pull towards each other as the fasteners are tightened to thereby clamp the handguard onto the barrel nut.
 20. The handguard of claim 11 wherein the means for engaging the barrel nut sprocket comprises a sprocket slot that slips over the sprocket to thereby attach the handguard to the barrel nut. 